Jack Andersen begins his professional career with the ThunderBolts in 2018. He signed on October 16, 2017 after four years at the University of Illinois-Chicago. He started 13 games for the Flames as a senior and went 5-2 with a 3.30 ERA and 51 strikeouts in 71 innings on his way to being named Second Team All-Horizon League. Overall, he appeared in 64 collegiate games (40 starts), amassing 16 wins and three saves with a 4.48 ERA. Jack attended Fremd High School in Palatine, Illinois.